linux-kernel - Re: [PATCH] Re: [2.6.20] BUG: workqueue leaked lock

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Message-ID: <20070321152935.GA215@tv-sign.ru>
Date:	Wed, 21 Mar 2007 18:29:35 +0300
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Jarek Poplawski <jarkao2@...pl>
Cc:	Neil Brown <neilb@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Folkert van Heusden <folkert@...heusden.com>,
	linux-kernel@...r.kernel.org,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] Re: [2.6.20] BUG: workqueue leaked lock

On 03/21, Jarek Poplawski wrote:
>
> > Sorry, I can't understand you. lockdep_depth is counted within a process,
> > which starts before f(), yes. This process is cwq->thread, it was forked
> > during create_workqueue(). It does not take any locks directly, only by
> > calling work->func(). laundry_wq doesn't differ from keventd_wq or any other
> > wq in this sense. nfsd does not "runs kthread by itself", it inserts the
> > work and wakes up cwq->thread.
> 
> I think we know how it all should start and go. If only analyzing
> the code could be enough, this current check of lockdep_depth()
> is unnecessary too, because laundromat_code code looks as good
> as run_workqueue code. I send it for testing and I mean it -
> something strange is going here, so some checks should be added
> - I didn't say mine is the right and will certainly help.

Ah, sorry, I misunderstood you. I had (my fault) a false impression
that you propose this patch as a "fix", while we seem to agree that
the real source of this problem remains unknown.

> So, if
> you have another idea for looking after it, let us know.

No, I don't.

Oleg.

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